Disc apparatus

ABSTRACT

A disk apparatus ( 10 ) includes an optical pick-up ( 12 ) and a DSP ( 28 ), and irradiates a laser beam onto a recording surface of a disk recording medium ( 100 ) by the optical pick-up. In a case that a time period (access time period) required for a seek is shorter than a time period (changing time period) required for the number of rotations, the DSP does not simultaneously perform a change of the number of rotations and the seek. To the contrary, the DSP delays the seek by |access time period−changing time period|, and performs a recording and a reproduction after the change of the number of rotation is ended.

TECHNICAL FIELD

The present invention relates to a disk apparatus and a disk accessmethod. More specifically, the present invention relates to a diskapparatus and a disk access method that rotate by a motor a diskrecording medium in which a plurality of areas having optimum rotatingspeeds different to each other are allotted to a recording surface, andradiate by an optical pick-up a laser beam onto any one of the pluralityof areas.

PRIOR ART

A disk 10 used in a conventional kind of a disk apparatus and an accessmethod is formed with a track in a spiral manner as shown in FIG. 3.This track is formed of a plurality of zones 100 a having the disk 100divided in a radial direction. The number of sectors 100 b included inone track (in a colloquial sense that donates one circumference.Hereinafter, the same is true.) is the same in the same zone 100 a. Inaddition, the outer the zone 100 a on an outer circumferential side, themore sectors 100 b included in one track.

In the conventional kind of the disk apparatus, in order to render arecording density of each sector 100 b equal, the disk 100 is made torotate in a ZCLV (Zone Constant Linear Velocity) system. Therefore, themaximum rotating speed of the disk 100 is the same in the same zone asshown in FIG. 4(A), and the rotating speed gradually becomes slowly inproportion to a distance from the inner circumferential side to theouter circumferential side.

In a case of managing a file by an FAT (File Allocation Table) system ora UDF (Universal Disk Format) system, the sector 100 b of an accessdestination strides over the zone, and at this time, it is needed tochange the rotating speed of the disk 100, that is, to change therotating speed of a spindle motor. In addition, the further the zone 100a to each other (the longer a distance of the seek), the larger adifference of the rotating speed between before and after the change,and thus, a time period for changing the rotating speed becomes longerby that difference.

Furthermore, as a conventional disk apparatus, disclosed in JapanesePatent Laying-open No. 11-66726 [G11B 19/28 7/00 19/247 20/10] laid-openon Mar. 9, 2000, is a disk apparatus using a ZCLV system for rotatingthe disk at a time of recording a signal, and using a ZCAV (ZoneConstant Angular Velocity) system for rotating the disk 100 in order toincrease the speed of a process at a time of reproducing the signal. Asshown in FIG. 4(B), the rotating speed is approximately constant by theZCAV system irrespective of the zone. Thus, in such the disk apparatus,on one hand, the time period required for the seek is negligible whenthe process is switched from the recording to the reproducing in thezone on the outer circumferential side. On the other hand, the timeperiod required for changing the rotating speed becomes long.

When the time period required for changing the rotating speed becomeslong, a following problem occurs. When it is intended to read out asignal (file) from the plurality of sectors 100 b formed in the zones100 a different to each other, the sector 100 b on the outercircumference is accessed (reproduced (2)) after accessing (reproducing(1)) the sector 100 b on the inner circumference, it is needed toincrease the rotating speed of the disk 100 as shown in FIG. 5.

As shown in FIG. 5, in a case that the time period (hereinafter referredto as a “changing time period” or a “second time period”) required forchanging this rotation speed is longer than the time period (hereinafterreferred to as a “seek time period” or a “first time period”) requiredfor the seek, the seek is ended before the changing of the rotatingspeed is completed, and a reproduction (2) is executed. At this time,the rotating speed does not reach an intended rotating speed so that thereproduction (2) is unsuccessful, and then, the reproduction isre-tried. In total, there are twelve kinds of check items for retryingsuch as an excess or deficiency of the laser power, a deviance of aphase of data, and etc. There are the twelve items so that it is neededto retry up to a maximum of twelve times. This leads to a problem that aprocess of the reproduction (2) becomes slow by these 12 times.

SUMMARY OF THE INVENTION

Therefore, it is a primary object of the present invention to provide anovel disk apparatus and disk access method.

It is another object of the present invention to provide a diskapparatus and a disk access method capable of improving a disk accesscharacteristic.

A first invention is a disk apparatus that rotates by a motor a diskrecording medium in which a plurality of areas having optimum rotatingspeeds different to each other are allotted to a recording surface, andirradiates by an optical pick-up a laser beam to any one of theplurality of areas, and comprises: a mover for moving, when a currentarea to which the laser beam is irradiated at this time and a desiredarea to which the laser beam is intended to be irradiated do not agree,the optical pick-up to a location corresponding to the desired area; achanger for changing, when the current area and the desired area do notagree, a rotating speed of the motor to the optimum rotating speed ofthe desired area; and a delayer for delaying when a first time periodrequired for moving the optical pick-up by the mover is shorter than asecond time period required for changing the rotating speed by thechanger, a start of moving the optical pick-up by the mover by a delayedtime period that corresponds to a difference between the first timeperiod and the second time period.

A second invention is a disk access method that rotates by a motor adisk recording medium in which a plurality of areas having optimumrotating speeds different to each other are allotted to a recordingsurface, and irradiates by an optical pick-up a laser beam to any one ofthe plurality of areas, and comprises following steps of: (a) moving,when a current area to which the laser beam is irradiated at this timeand a desired area to which the laser beam is intended to be irradiateddo not agree, the optical pick-up to a location corresponding to thedesired area; (b) changing, when the current area and the desired areado not agree, a rotating speed of the motor to the optimum rotatingspeed of the desired area; and (c) delaying, when a first time periodrequired for moving the optical pick-up in the step (a) is shorter thana second time period required for changing the rotating speed in thestep (b), a start of moving the optical pick-up in the step (a) by adelayed time period that corresponds to a difference between the firsttime period and the second time period.

In the present invention, in a disk apparatus that rotates by a motor adisk recording medium in which a plurality of areas having optimumrotating speeds different to each other are allotted to a recordingsurface, and irradiates by an optical pick-up a laser beam to any one ofthe plurality of areas, in a case that a moving time period of theoptical pick-up to a desired area to which the laser beam is irradiatedis shorter than a time period until the optimum rotating speed of thedesired area is reached, a start of moving the optical pick-up isdelayed, and the laser beam is irradiated to the desired area after theoptimum rotating speed is reached.

That is, when a current area to which the laser beam is irradiated atthis time and a desired area to which the laser beam is intended to beirradiated do not agree, the mover moves the optical pick-up to alocation corresponding to the desired area, and when the current areaand the desired area do not agree, the changer changes a rotating speedof the motor to the optimum rotating speed of the desired area.

In addition, when a first time period required for moving the opticalpick-up by the mover is shorter than a second time period required forchanging the rotating speed by the changer, a start of moving theoptical pick-up by the mover is delayed by a difference between thefirst time period and the second time period.

As a consequence, eliminated is a situation where a writing and areading into/from the disk recording medium are performed in a state inwhich the rotating speed is too fast or too slow, and an unsuccessfulwriting and reading that result from an excess or deficiency of therotating speed are prevented, thus restraining an occurrence of are-trial.

According to the present invention, it is possible to shorten a timeperiod required for an operation of the writing and reading into/fromthe disk recording medium.

The above described objects and other objects, features, aspects andadvantages of the present invention will become more apparent from thefollowing detailed description of the present invention when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an overview of a disk apparatus;

FIG. 2 is a flowchart showing an operation of a FIG. 1 embodiment;

FIG. 3 is an illustrative view showing a magnetooptical disk;

FIG. 4 is an illustrative view showing as a model a difference of arotating speed of the magnetooptical disk, FIG. 4(A) is an illustrativeview showing the rotating speed by a ZCLV system, and FIG. 4(B) is anillustrative view showing the rotating speed by a ZCAV system;

FIG. 5 is an illustrative view showing a change of the rotating speedand a processing timing of the magnetooptical disk in a conventionaldisk apparatus; and

FIG. 6 is an illustrative view showing a change of the rotating speedand a processing timing of the magnetooptical disk, FIG. 6(A) is anillustrative view showing a timing of the conventional disk apparatus,and FIG. 6(B) is an illustrative view showing the timing of the diskapparatus of the FIG. 1 embodiment.

BEST MODE FOR PRACTICING THE INVENTION

Referring to FIG. 1, a disk apparatus 10 of this embodiment includes anoptical pick-up 12. A location of the optical pick-up 12 in a radiusdirection of the magnetooptical disk 10 is controlled by a sledservomechanism 34. In addition, a location of an optical lens 12 aprovided in the optical pick-up 12 in an optical axis direction iscontrolled by a focus servomechanism 30. Furthermore, a location of theoptical lens 12 a in a radius direction of the magnetooptical disk 100is controlled by a tracking servomechanism 32.

In a laser drive 36, a laser power value is set by a control signalapplied from a DSP 28, and the laser drive 36 allows a laser beam of theset laser power value to be output from a laser diode 12 b. The laserbeam output from the laser diode 12 b is converged by the optical lens12 a, and irradiated onto a recording surface of the magnetooptical disk100.

The magnetooptical disk 100 includes a reproducing layer and a recordinglayer, and a desired signal is recorded in the recording layer. When thedesired signal is recorded in the recording layer, the laser beam isirradiated onto the recording layer via the optical lens 12 a focused onthe recording layer and the reproducing layer. When a magnetic field isapplied by a magnetic head 14 to the recording layer having a Curietemperature reached by the laser beam, a portion having the Curietemperature reached in the recording layer is magnetized toward amagnetic field direction. Each magnetized portion is referred to as amark. By controlling the magnetic field produced by the magnetic head14, the desired signal is recorded in the recording layer of themagnetooptical disk 100.

On the other hand, when the signal is read out from the magnetoopticaldisk 100, the laser beam is irradiated onto the reproducing layer viathe optical lens 12 a focused on the reproducing layer. The reproducinglayer that has reached a predetermined temperature (temperature lowerthan the Curie temperature) by a radiation of the laser beam indicates amagnetism, and is magnetized corresponding to the magnetic fieldretained by the mark in the recording layer. The laser beam reflected inthe reproducing layer is deflected corresponding to a direction of themagnetic field of the reproducing layer, and the optical pick-up 12reads the signal based on a deflecting state of the reflected laserbeam.

The recording layer is raised to the Curie temperature so that arecording laser beam needs an output (power) greater than a reproducinglaser beam. In addition, the temperature at which the reproducing layerindicates the magnetism is determined in advance. However, an intensityof the laser beam necessary for reaching the temperature differsdepending on the temperature of the magnetooptical disk 100. Therefore,besides an optimum recording laser power value, the optimum reproducinglaser power value, too, depends on the temperature of the magnetoopticaldisk 100. It is noted that an ambient temperature of the magnetoopticaldisk 100 is measured by a temperature sensor 44, and its measurementresult is applied to the DSP 28.

When the desired signal is recorded in the magnetooptical disk 100, anECC encoder 18 attaches an error correcting code (ECC) to an inputsignal, and renders the signal to which the error correcting code isattached an encode signal. The magnetic head 14 produces the magneticfield corresponding to the encode signal applied from the ECC encoder18.

Herein, the error correcting code is a code attached to each signal of apredetermined amount, and the signal of the predetermined amount towhich the error correcting signal is attached is referred to as an ECCblock. The ECC block is constructed of a group of signals that isreferred to as a plurality of lines. An ECC decoder 22 described lateris capable of automatically correcting an erroneous signal (hereinafterbriefly referred to as an “error signal”) based on the error correctingcode when an error is included in a digital signal within the block.However, a signal amount of a correctable error signal has apredetermined limit.

When the signal recorded in the magnetooptical disk 100 is reproduced,the laser diode 12 b is controlled by the laser drive 36, and the laserdiode 12 b outputs the laser beam corresponding to the control. Theoutput laser beam is irradiated onto a surface of the magnetoopticaldisk 100 via the optical lens 12 a. A reflected light from the surfaceof the magnetooptical disk 100 permeates through the same optical lens12 a, and is incident onto a light detector 12. The light detector 12 capplies a signal (RF signal) corresponding to the incident light to anequalizer 16. The equalizer 16 compensates a frequency characteristic ofthe RF signal, and applies the same to an RPML (Partial Response MaximumLikelihood) circuit 20. The RPML circuit 20 generates the digital signalbased on the RF signal, and applies the generated digital signal to theECC decoder 22. The ECC decoder 22 applies an error correction to theerror signal included in the digital signal received from the PRMLcircuit 20 by each one ECC block. In addition, the ECC decoder 22applies to a code error rate calculating circuit 24 information(hereinafter briefly referred to as “correcting amount information”)indicating how many error signals are corrected in one line of the ECCblock, that is, how many error signals are included in one line. Thecode error rate calculating circuit 24 calculates a code error ratebased on the correction amount information applied from the ECC decoder22, and applies the same to the DSP 28.

The magnetooptical disk 100 is mounted on a spindle (not shown), and thespindle is coupled to a spindle motor 40 via a shaft 42. The DSP 28applies the control signal to a spindle servomechanism 38, and thespindle servomechanism 38 rotates the spindle motor 40 based on areceived control signal. In conjunction therewith, the shaft 42 isrotated, and the spindle, that is, the magnetooptical disk 100, isrotated. In addition, the spindle motor 40 produces an FG signalcorrelated with a rotating speed of the spindle, and applies this FGsignal to the DSP 28. As a result of the DSP 28 monitoring this FGsignal, the spindle coupled to the shaft 42, that is, the rotating speedof the magnetooptical disk 100 is appropriately controlled. This controlallows the magnetooptical disk 100 to be rotated by the ZCLV system at atime of recording the signal, and rotated by the ZCAV system at a timeof reproducing the signal.

As described above, by the ZCLV system, if a zone 100 a to which asector 100 b onto which the laser beam is irradiated belongs differs,the rotating speed of the magnetooptical disk 100 is changed. Inaddition, if a switch is made between the recording and the reproducing,a disk rotating method is switched between the ZCLV system and the ZCAVsystem so that the rotating speed of the magnetooptical disk 100 ischanged.

A time period required for changing this rotating speed is maximum whenthe recording/reproducing is switched for performing verifying after therecording, for example, in an outermost circumference of themagnetooptical disk 100 as understood from FIGS. 4(A) and (B). At thistime, a time period (seek time period: a first time period) for movingthe optical pick-up 12 is an almost negligible time period. In contrary,it takes approximately 300 ms for changing the rotating speed (changingfrom approximately 2000 rpm to approximately 3000 rpm).

In this case, as shown in FIG. 6(A), if the seek and the reproducing(verifying) are performed immediately after the recording, thereproducing is performed in a state that the intended rotating speed isnot satisfied. As a consequence, the reproduction is not properlyperformed, and therefore, the reproduction is retried by changing apower value, a phase of the data, and etc. When the reproducing isperformed besides the retrial, the seek is performed before two tracksof a desired track, and then, the reproduction is prepared. Thereafter,the reading is performed from the desired track. A most portion of thetime period required for the retrial is a time period required fortracing these two tracks.

That is, if the rotating speed is 2500 rpm, one retrial takesapproximately 50 ms according to Equation (1). In total, there are 12kinds of items to be confirmed regarding the retrial such as an excessor deficiency of the laser power, a deviance of the phase of the data,and etc. Therefore, if the retrial is made for each of all the 12 kindsof items, it is understood that it takes a maximum of approximately 600ms of more time period than Equation (2) (that is, 12 tracing timeperiods of the two tracks).2×60/2500=48  (1)50×12=600  (2)

The DSP of the disk apparatus 10 receives an instruction of a systemcontroller 50 (see FIG. 1) of a host so as to perform operations such asrecord, reproduce, retry, and so forth. Herein, the host corresponds toa CPU of a personal computer if the disk apparatus 10 is a driveapparatus of the personal computer, and corresponds to a CPU of adigital camera if the disk apparatus 10 is the drive apparatus of thedigital camera.

In a case that the reproducing is performed in a state that the intendedrotating speed is not satisfied so that it is not capable of reading, acommand of the retrial is transmitted from the system controller 50 ofthe host so as to perform the retrial. In this retrial, despite a factthat the rotating speed is the cause, the reproducing is performed bychanging the laser power value as described above, and changing thephase of the data. The rotating speed is the cause, and therefore, evenif the razor power is changed, and the phase of the data is changed, theretrial is not successful (in the items to be confirmed regarding theretrial, a confirmation of the rotating speed is not included). Even ifthe intended rotating speed is reached in the course of the retrial,which defines 12 retrials as one set, the laser power value and thephase of the data have been changed so that the retrial will notsucceed. Therefore, even if the intended rotating speed is reached, itwill not be successful to verify (reproduce) until the system controller50 of the host once again issues a read command after the retrial, whichdefines 12 retrials as one set, is completed. That is, in theconventional disk apparatus, even if the intended rotating speed isreached, the retrial is not successful for as long as a maximum ofapproximately 600 ms. This produces a wasteful time period, and thus, areproducing operation is delayed.

In order not to produce such the wasteful time period, the retrial as aresult of the excess or deficiency of the rotating speed may not beproduced. Consequently, in the disk apparatus 10 of this embodiment, inorder to prevent the retrial resulting from the excess or deficiency ofthe rotating speed from occurring, in a case that the time period(access time period: first time period) for allowing the optical pick up12 to seek is shorter than the time period (second time period) requiredfor changing the rotating speed to the intended rotating speed, as shownin FIG. 6(B), the time period for starting the seek is made to bedelayed by a time period of a difference between the first time periodand the second time period. In addition, the reproducing (or recording)is started only after the intended rotating speed (optimum rotatingspeed) is reached.

Below is a description regarding an operation of the DSP 28 of the diskapparatus 10 of this embodiment using a flowchart in FIG. 2. It is notedthat FIG. 2 only shows a process of an access request to themagnetooptical disk 100.

First, if there is a reproducing request such as the verifying after thewriting into the magnetooptical disk 100, it is determined that this isthe access request in a step S1. In a case of not being the accessrequest, another process is executed in a step S19.

If it is determined that this is the access request is determined, theoptimum rotating speed of the zone 100 a in which the sector of anaccess destination is included is calculated in a step S3. At this time,it is determined whether it is the access for the writing or the accessfor the reading, and in a case of the access for the writing, it isfurther determined in which zone 100 a the writing is performed, andthen, the optimum rotating speed is determined.

When the optimum rotating speed is determined, the DSP 28 applies thecontrol signal to the spindle servomechanism so as to start changing therotating speed of a stepping motor in a step S5.

In addition, in a step S7, the time period (hereinafter referred to as a“rotating speed changing time period: Tr”) required for changing therotating speed is calculated according to Equation (3).Tr=(|Rp−Rc|/ΔR)×Trio  (3)

It is noted that:

Rc: intended rotating speed (optimum rotating speed);

Rc: current rotating speed;

ΔR: difference of the rotating speed between an innermost circumferenceand an outermost circumference; and

Trio: time period required for changing the optimum rotating speed ofthe innermost circumference to the optimum rotating speed of theoutermost circumference.

Subsequently, in a step S9, the time period (hereinafter referred to asan “access time period: Ta”) required for accessing an intended addressis calculated according to Equation (4).Ta=(|Lp−Lc|/ΔL)×Taio  (4)

It is noted that:

Lp: location of the intended address;

Lc: location of the current address;

ΔL: difference between the location of an innermost circumferenceaddress and an outermost circumference address; and

Taio: time period required for accessing the address location of theinnermost circumference to the address location of the outermostcircumference.

Furthermore, in a step S1, by comparing the rotating speed changing timeperiod Tr and the access time period Ta, it is determined whether or notthe access time period Ta is shorter than the rotating speed changingtime period Tr. In a case that the access time period Ta is not shorterthan the rotating speed changing time period Tr, the access (seek) isstarted in a step S15, and when the access is completed, the writing orreading of the signal is performed in a step S17.

On the other hand, in a case that the access time period Ta is shorterthan the rotating speed changing time period Tr, the process is waitedby a difference between the rotating speed changing time period Tr andthe access time period Ta in a step S13. In addition, the access (seek)is started in the step S15, later. The magnetooptical disk 100 reachesthe intended rotating speed (optimum rotating speed) by the time ofcompleting this seek so that the reading (or writing) is performed inthe step S17.

As described above, in the disk apparatus 10 of this embodiment, in acase that the access time period Ta is shorter than the rotating speedchanging time period Tr, the access (seek) is delayed by a differencebetween the rotating speed Tr and the access time period Ta, and thereading or writing is performed only after the seek is completed and themagnetooptical disk 100 reaches the intended rotating speed.

Therefore, the reading or the writing is performed only after themagnetooptical disk 100 reaches the intended rotating speed so that itis possible to prevent the retrial (maximum of 12 reproductions)resulting from the excess or deficiency of the rotating speed, thusshortening an operating time period of the recording or the reproducing.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A disk apparatus that rotates by a motor a disk recording medium inwhich a plurality of areas having optimum rotating speeds different toeach other are allotted to a recording surface, and irradiates by anoptical pick-up a laser beam to any one of said plurality of areas,comprising: a mover for moving, when a current area to which said laserbeam is irradiated at this time and a desired area to which said laserbeam is intended to be irradiated do not agree, said optical pick-up toa location corresponding to said desired area; a changer for changing,when said current area and said desired area do not agree, a rotatingspeed of said motor to the optimum rotating speed of said desired area;and a delayer for delaying, when a first time period required for movingsaid optical pick-up by said mover is shorter than a second time periodrequired for changing said rotating speed by said changer, a start ofmoving said optical pick-up by said mover by a delayed time period thatcorresponds to a difference between said first time period and saidsecond time period.
 2. A disk apparatus according to claim 1, whereinsaid changer rotates said motor by a ZCLV system at a time of writinginto said disk recording medium, and rotates said motor by a ZCAV systemat a time of reading out from said recording medium.
 3. A disk accessmethod that rotates by a motor a disk recording medium in which aplurality of areas having optimum rotating speeds different to eachother are allotted to a recording surface, and irradiates by an opticalpick-up a laser beam to any one of said plurality of areas, comprisingfollowing steps of: (a) moving, when a current area to which said laserbeam is irradiated at this time and a desired area to which said laserbeam is intended to be irradiated do not agree, said optical pick-up toa location corresponding to said desired area; (b) changing, when saidcurrent area and said desired area do not agree, a rotating speed ofsaid motor to the optimum rotating speed of said desired area; and (c)delaying, when a first time period required for moving said opticalpick-up in said step (a) is shorter than a second time period requiredfor changing said rotating speed in said step (b), a start of movingsaid optical pick-up in said step (a) by a delayed time period thatcorresponds to a difference between said first time period and saidsecond time period.